Recently, wireless LAN technologies, such as IEEE 802.11 or ETSI Hiperlan 2, have been developed that may be used in conjunction with existing networks, including mobile networks, i.e., 3G or 2G, to provide various services. The wireless LAN services provide the advantages of faster data speeds, generally on the order of about ten times faster than those provided by a 3G network, but are much more limited in the area of coverage and the number of users that can be connected to the base station. It is envisioned that a mobile terminal user would transition from a mobile telephony network to a wireless LAN upon entering a coverage area of the wireless LAN, and transition to the mobile telephony network upon leaving the coverage area of the wireless LAN. In order to facilitate the interconnection between the services provided by the mobile networks and the wireless LANs, it is desirable that the wireless LANs provide the same services expected from a 3G network.
One such important feature of a mobile network, such as a 3G network, is the ability to page a mobile terminal, that is, the ability for the core network to page the mobile terminal that is not currently connected to the access network. A mobile network is essentially made up of a radio access network and a core network. A mobile terminal has a relationship with the core network through the radio access network. That is a mobile terminal needs to be connected to the radio access network in order to communicate with the core network. During periods when the mobile terminal is not required to be directly communicating with the core network the mobile terminal may enter an IDLE mode to save radio resources and to conserve power. In such a mode, the mobile terminal is not connected with the access network. If the core network needs to communicate with the mobile terminal, then the core network requests that the radio access network page the mobile terminal. The paging mechanism is generally implemented within the radio interface between the mobile terminal and the base station. The paging process comprises initiating a downlink broadcast from the network to the mobile terminal that requests that the mobile terminal connect to the radio access network. The mobile terminal determines the presence of the downlink broadcast, and in response, develops a connection with radio access network to communicate with the core network. In this manner, a mobile terminal does not need to be permanently connected to the radio access network, and thus, consume resources of the access network.
However, such paging capability is not available between a mobile terminal and a base station in current wireless LANs, for example a wireless LAN based on the Hiperlan 2 Technical Specification. In current wireless LAN arrangements, the mobile terminal must be permanently connected to the base station, or “access point,” in order for the mobile terminal to detect a downlink message. However, having a mobile terminal permanently connected to the access point requires that resources be provisioned for that mobile terminal. In a Hiperlan 2 network, connection to the access point requires that a MAC ID addressed be reserved for that mobile terminal. However, the number of MAC ID addresses available for a specific access point is generally limited. In a Hiperlan 2 network, the number of addresses is limited to less than 250. Therefore, a problem may arise in the availability of network resources if the total number of mobile terminal that desire to be connected to a particular access point, or receive downlinks through the particular access point, exceeds 250.
Some wireless LAN arrangements, including Hiperlan 2 may allow a mobile terminal to enter a SLEEP mode, wherein the mobile terminal goes to a low power mode without losing data. In such a mode, the mobile terminal wakes up at specific intervals negotiated with the access point to check whether any pending messages have been buffered for the mobile terminal. If there is a pending message, the mobile terminal leaves the SLEEP mode and enters an ACTIVE mode to receive and process the pending message. However, the SLEEP mode is not suitable for implementing a paging mechanism between the base station and the mobile terminal because the mobile terminal must still connect to the base station when checking for buffered messages. The mobile terminal is still seen by the access point as a connected device, even while the mobile terminal is in the SLEEP mode. Therefore, a MAC ID must be allocated and some resources must be provisioned for that mobile terminal. This means that the total number of mobile terminals that can be connected, or periodically receive downlink messages remains the same.
Another potential method of implementing a paging mechanism between an access point and a mobile terminal might be for the mobile terminal to actually disconnect from the access point and periodically connect to the access point in order to check with the corresponding convergence layer to determine whether downlink messages are pending. However, this requires the mobile terminal to initiate the association procedure each time it connects with the access point, which is power consuming. Furthermore, if all mobile terminals need to be periodically associated just for paging polling purposes, the procedure is radio resource and MAC ID consuming, whereas only one device may be affected by the paging.
Therefore, there is a need for an apparatus and a method for implementing a paging mechanism between an access point and a mobile terminal in a wireless LAN that does not require the mobile terminals to be permanently connected to, or to periodically associate with, an access point.